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Format JSON, decode JWTs, build fluid CSS or draw diagrams. Everything is processed in your browser: what you paste is never sent to a server and stays on your device.
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All tools
Every entry is a concrete tool with the name you'd search for.
- JSON FormatterFormat, minify and validate JSON with every error marked.
- JSON to TypeScriptGenerate TypeScript interfaces or types from a JSON sample.
- JSON to ZodGenerate a ready-to-use Zod validation schema from JSON.
- JSON Mock GeneratorGenerate realistic fake records with the structure of your JSON.
- JSON DiffCompare two JSON documents and list the differences by path.
- JSON ↔ YAMLConvert JSON to YAML and back, with YAML indentation errors marked.
- JSON ↔ CSVConvert a JSON array to CSV for Excel, and back. Nested objects flattened.
- JWT DecoderDecode a JWT, check its expiry and verify its signature.
- JWT GeneratorCreate and sign test JWTs with HS256, RS256, ES256 and more.
- URL ParametersBreak a URL into a decoded key/value table and rebuild it.
- Base64Encode and decode Base64 and Base64URL, text and files.
- URL EncodeEncode and decode text for URLs: encodeURIComponent vs encodeURI.
- HTML EntitiesConvert special characters to HTML entities (&, <, é) and back.
- UnicodeSee the code point, escapes and UTF-8 bytes of every character.
- Hex ↔ BinaryConvert numbers and text between hex, binary, octal and decimal.
- PunycodeConvert domains with accents or non-Latin characters to xn-- and back.
- GzipCompress or decompress text with gzip/deflate, as Base64.
- HashMD5, SHA-1, SHA-256, SHA-384 and SHA-512 of a text or file at once.
- HMACCompute and verify HMAC signatures, e.g. for Stripe or GitHub webhooks.
- UUIDGenerate UUID v4 and v7 in bulk, and validate or identify a UUID.
- BcryptHash a password with bcrypt and check a password against a hash.
- Password generatorSecure passwords and random secrets for .env files, with entropy.
- RSA/EC keysGenerate RSA or elliptic-curve key pairs and convert PEM ↔ JWK.
- X.509 certificatesDecode a PEM certificate: issuer, SAN domains, validity and fingerprint.
- Group name (optional)Build regular expressions by dragging blocks in plain language.
- Regex TesterTest a regex against many strings, with matches, groups and an explanation.
- Common RegexReady-made, explained patterns: email, URL, DNI/NIE, IBAN, phone…
- TimestampConvert Unix epoch (s, ms) to ISO 8601 and readable dates, and back.
- Time zonesSee a date and time in several time zones at once, for meetings.
- Date differenceTime between two dates (days, hours, business days) and date arithmetic.
- CronExplain a cron expression in plain words and see its next runs.
- cURL → fetchConvert a cURL command (Copy as cURL) to fetch, axios or Angular HttpClient.
- HTTP status codesSearchable cheat sheet of every HTTP status code and when to use it.
- HTTP headersExplain response headers and spot missing security headers (CSP, HSTS…).
- Meta tagsPreview your page in Google, LinkedIn, X and WhatsApp and get the meta tags.
- User-AgentBreak a User-Agent into browser, engine, OS and device. Shows yours.
- SemverCheck if a version satisfies a range (^, ~, >=…) and sort versions.
- SQL FormatterFormat unreadable SQL queries or compact them into one line.
- SQL → ER diagramDraw the entity-relationship diagram of your CREATE TABLE statements.
- OpenAPI ViewerTurn an OpenAPI/Swagger file into navigable docs, with errors marked.
- JSON Schema ValidatorValidate JSON against a JSON Schema and see exactly which field fails.
- XML ↔ JSONConvert XML to JSON and back, keeping attributes. For SOAP and B2B APIs.
- XML FormatterFormat, minify and validate XML, with the error located.
- docker run → ComposeTurn docker run commands into a docker-compose.yml.
- CIDR CalculatorNetmask, first and last IP, hosts and membership of a subnet.
- chmod CalculatorTick the permissions and get 755 / rwxr-xr-x, or the other way round.
- .env ↔ JSONConvert .env files to JSON and back, catching duplicate keys and bad quotes.
- Markdown EditorWrite Markdown with a live GitHub-style preview, Mermaid diagrams and HTML export.
- NameConvert HTML into valid JSX for React: className, style objects, self-closing tags.
- Case ConverterConvert identifiers between camelCase, snake_case, kebab-case, PascalCase and more.
- Text DiffCompare two texts or code side by side, with changes highlighted by line and word.
- Keyboard Event TesterPress any key to see event.key, event.code, keyCode and modifiers.
- CSS clamp() GeneratorFluid font sizes with clamp(), mixing rem and vw.
- Fluid Type ScaleGenerate a fluid typographic scale with clamp(), as CSS variables or a Tailwind theme.
- NameConvert colors between HEX, RGB, HSL, OKLCH and CSS names.
- NameGenerate a Tailwind-style 50–950 palette from one color.
- Contrast CheckerCheck WCAG contrast between text and background, with the fix to pass.
- Box-shadow GeneratorDesign layered CSS shadows visually and copy the CSS.
- CSS Gradient GeneratorCreate linear, radial and conic gradients with several color stops.
- cubic-bezier EditorDesign CSS easing curves by dragging the points and preview the animation.
- px ↔ remConvert between px, rem and em, one value or a whole CSS block.
- SVG OptimizerClean and shrink SVGs with SVGO, with before/after preview and savings.
- ComponentTurn an SVG into a React/TSX icon component with size and currentColor.
- App nameGenerate favicon.ico, Apple and PWA icons, the manifest and the tags from one image.
- WebP ConverterConvert images to WebP or AVIF with adjustable quality and compare the size.
- QR Code GeneratorCreate QR codes for text, URLs, WiFi or contacts, with colors and a logo.
Made by a web developer, for web developers
kitforweb is a free, open-source side project with no ads and no trackers. If it saves you time, you can buy me a coffee to keep it going.